1. Field
The application generally relates to communication networks and communication systems, including wideband and ultra-wideband communication systems. In particular, the application relates to systems and methods for reducing the amount of data traffic on a feedback channel between a receiver and a transmitter.
2. Background
Wireless communication systems are widely deployed to provide various types of communication such as voice, packet data, and so on. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources. Examples of such multiple-access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, and orthogonal frequency division multiplexing (OFDM) systems. Many forms of wireless communication systems use a feedback channel to improve the performance of the system. As data is sent between a transmitter and a receiver, the conditions of the communication channel being used may change. For example, as the receiver moves farther away from the transmitter, the communication channel conditions may degrade. The communication channel may also comprise a plurality of sub-carriers. Generally, the feedback channel is used by the receiver to transmit information about these changes in channel conditions to the transmitter. The information transmitted by the receiver on the feedback channel is often referred to as channel state information (CSI). In one embodiment, CSI may comprise an estimate or information about channel conditions for a certain channel. In another embodiment, CSI may comprise at least one of carrier-to-noise ratio (CNR), signal-to-noise ratio (SNR), received signal strength indicator (RSSI), signal-to-interference-and-noise-ratio (SINR), a signal strength, a noise level, and a data rate. It may also be referred to as channel quality indicator (CQI).
Generally, the CSI is sent from the receiver to the transmitter and may consume significant amounts of signaling resources. The CSI may provide, to the transmitter, data indicative of channel conditions obtained by the receiver. In one embodiment, the transmitter uses the CSI to control certain transmitter parameters including but not limited to, transmit signal power, data rate, or modulation and coding scheme. The CSI may be sent using CSI packets (e.g., packets sent from the receiver to the transmitter, which contain CSI). A plurality of CSI packets may be sent to the transmitter for a single feedback updates (e.g., an update that provides CSI for channel). In multicarrier-based wideband (WB) and ultra-wideband systems (UWB), e.g., OFDM-based systems, the feedback channel may be used to provide information for the plurality of subcarriers (e.g., tones). The feedback channel is responsible for providing CSI for the individual subcarriers on a timely basis, so that the transmitter may act on the available information. For example, if a transmitter receives CSI indicating that channel conditions have degraded, the transmitter may decide to transmit at a slower data rate. Thus, it is desirable to preserve signaling resources by reducing the amount of data traffic transmitted over feedback channels.